Meriweather --
I've never gone the voucher route for APs -- I've usually just gotten mine at the ticket booth or in the mail. So I am not completely up to date on what happens with the vouchers in relation to the activation date. Is it still the case where, if you have a voucher, the AP is not officially activated until you bring the voucher to DLR? If so, then I would get the vouchers as soon as possible if you can swing it.
To be honest, you can never be completely certain of what Disney is going to do with their ticket price increases. Often times, just when we think we have them nailed down to a predictable pattern, they switch things up on us! Last year the prices went up on or around May 18th, I think it was, but if they begin rolling out any of the new entertainment for the 60th anniversary prior to that time, they could raise the prices even sooner. They could suddenly decide to raise them in March. There's no telling what will happen.
There was one instance -- and it was sometime in the last 5 or 6 years but I can't recall exactly when -- in which the prices were increased at least 2 (if not 3) times within a 12-month time frame. There was a regular summer increase, then a small increase in January and then another increase in late spring or early summer, as I recall! And then there was one year when the APs got hit with a huge increase -- much bigger than normal -- and that shocked everyone!